chore(deps): update postgres docker tag to v13.15

data/linux_amd64/docker-compose.yml

@@ -34,7 +34,7 @@ services:
       driver: "local"
 
   db:
-    image: postgres:13.8-alpine@sha256:fc3670fa23119159394dfdb98eee89b30ef5a506791aea6ff7d8a4e73a8cd4a4
+    image: postgres:13.15-alpine@sha256:c1ec55f10506775b62f85eefc61a594bc78366a7499f9eb007945fb3b4cd1584
     environment:
       - POSTGRES_DB=owncloud
       - POSTGRES_PASSWORD=owncloud